The Trump administration has asked Congress for more funding to meet a very ambitious deadline.

On their last morning on the moon, the astronauts woke up to horns, trumpets, and thumping drums. They recognized the sound immediately—it was the theme from 2001: A Space Odyssey.

“That was a great song,” Gene Cernan told mission control. “I think it’s very apropos at the moment.”

It was 1972, and Cernan was on humankind’s sixth odyssey to the surface. After three days of work on the rocky terrain, backed by surreal views, he and the other astronauts came home. No one has been back since.

Not for long, according to the Trump administration. President Donald Trump wants NASA to return astronauts to the surface of the moon in 2024. To get there, the president announced Monday that his administration would ask for another $1.6 billion in NASA’s budget for the coming fiscal year.

“Under my administration, we are restoring NASA to greatness,” Trump said in a tweet on Monday night.

The tweet, resolute and sprinkled with capital letters, exuded confidence and determination. The administration would like this projected mission to be treated, in advance, as a historic event: The mission has been named Artemis—sister of Apollo—because, officials say, it will put the first woman on the moon. In Trump’s telling, the moon mission sounds inevitable, and success guaranteed.

It’s not.

By space-exploration measures, 2024 is right around the corner. To make that goal, NASA would need to launch astronauts inside a crew capsule (that is still being tested) on a giant rocket (that has never flown before) to a floating station around the moon (that doesn’t yet exist) and drop them to the surface in lunar-specific spacesuits (that don’t exist, either). In Greek mythology, Artemis and Apollo are twins, but while the Apollo-era missions were fed with a massive budget, this new Artemis mission is off to a smaller start.

To help fund its wild ambitions, the Trump administration has tacked on $1.6 billion to its proposal for NASA for the next fiscal year, a request that goes to Congress, which decides how much to give the agency. The money, officials say, will go toward boosting the work NASA is already doing, like developing the crew capsule and rocket designed to carry astronauts toward the moon. But is it enough?

Jim Bridenstine, the NASA administrator, calls it a “down payment.” “In the coming years, we will need additional funds,” Bridenstine told reporters. “But this is a good amount that gets us out of the gate in a very strong fashion.”

He didn’t say how much the agency would need in the next fiscal year, and the one after that, but he did acknowledge that the $1.6 billion request is at “the low end” of what the agency needs to hit its 2024 target.

Despite these financial realities, the Trump administration insists the mission is feasible. We’ve already been to the moon, the message goes, we can do it again. Supporters point out that just eight years elapsed between John F. Kennedy’s declaration to go to the moon and Neil Armstrong’s first steps on the surface—and that was without the technology NASA has now.

To which critics respond, we’ve already gone to the moon. Why do it again?

According to Vice President Mike Pence, the same reason as last time—national pride and duty. “The rules and values of space, like every great frontier, will be written by those who have the courage to get there first and the commitment to stay,” the vice president said, when announcing the mission this spring.

President Trump has also shown interest in speeding up certain space efforts in an apparent attempt to bolster his legacy. Not long after his inauguration, he asked the acting NASA administrator whether the agency could land Americans on the surface of Mars before the end of his first term—“if we sent NASA’s budget through the roof,” as he put it, “but focused entirely on that instead of whatever else you’re doing now.” Just a few months ago, the administration was eyeing a 2028 landing, before moving the deadline way up.

This new budget request falls short of the “through the roof” threshold: Space-policy expert say the new proposal is modest. “It’s hard to imagine that much money wouldn’t give them the kickstart they need,” says Jared Zambrano-Stout, an aerospace consultant and former chief of staff for the White House National Space Council, which sets the agenda for NASA.

Casey Dreier, an adviser at the Planetary Society, a nonprofit space-advocacy group, predicts the agency would need between $4 billion and $5 billion per year for the next five years, rather than an annual $1 billion infusion. “If they’re proposing a total of $8 billion in five years … this ain’t gonna get us to the lunar surface in 2024,” he says.

Laura Forczyk, a space analyst and founder of Astralytical, a consulting firm, thinks the proposal was a savvy move. Congress was probably expecting an exorbitant number because, well, it’s coming from Trump. The president has asked for billions to fund his border wall, for example. “Projecting too much money over too long of a project timeline is what doomed Constellation,” Forczyk says, referring to a Bush-era space program that the Obama administration deemed too expensive and canceled in 2010. “Taking it year-by-year with incremental increases is a safer bet.”

In any case, the bottom line is that NASA will need more money than it has had in decades. The latest budget, $21.5 billion, is the agency’s largest in years. But it accounts for less than half a percent of the federal budget. At the peak of the Apollo program, the budget counted for more than 4 percent of federal spending.

The Trump administration’s moon dreams face a skeptical public. A Pew Research Center poll last year found that while most Americans believe it’s important for the United States to be a world leader in space exploration, only 13 percent said sending humans to the moon should be a top priority. About 63 percent said the agency’s primary focus should be climate research. (Americans weren't so jazzed about going to the moon in the 1960s either; polls from the time showed that a majority of the population didn’t think the Apollo program was worth the cost.)

His new effort also faces a skeptical Congress, unconvinced of the nationalist argument for more moon travel, and Democrats, mindful of that 2024 goal, gave Bridenstine an earful at a recent hearing about the moon mission.

So far, it’s not clear where the extra $1.6 billion will come from. Bridenstine said no NASA programs will be cut. The Associated Press reports that the money could be diverted from spending on Pell Grants, federal subsidies that help students pay for college education—a move unlikely to be popular with Democrats.

Space-exploration efforts have always taken longer than officials expect, usually because of a combination of technical challenges and financial restraints. Presidents who shepherd in new dreams are usually no longer in office when they become reality. Sometimes, entire programs get thrown out altogether under a new administration, and NASA is forced to start again on something new. George W. Bush instructed NASA to return Americans to the moon by 2020. Barack Obama canceled that plan, and told NASA to think about Mars instead. Now this administration wants to hit the moon again before going to Mars.

I asked Bridenstine how he would reassure the NASA engineers and scientists he’s asking to carry out this mission, knowing that a new administration could turn it upside down.

“NASA has a history of seeing these starts and stops,” he says. “And it is important for us to understand how important it is to get strong bipartisan support from the beginning.”

Artemis, the moon goddess, was a fierce warrior, one of the most inspiring in the pantheon. Her persona eschews the majority of mythology, which is rife with stories of women being chased, imprisoned, and punished by powerful men. This name pick, while refreshing—exciting, even— also applies some pressure. To put any name on the program makes it more real, more high stakes, and this one now has a powerful name to live up to. In a perfect scenario, with buckets of money and unwavering political will, NASA could make it back to the moon. In a realistic one, the only boot prints on the moon at the end of a Trump presidency might belong to space travelers from 1972.